In this research, three different types of biocomposites were made from kenaf fiber/soy protein, kenaf fiber/DS 3530, and kenaf fiber/soy protein/DS 3530. Fourier transform infrared spectra of the biocomposites showed that there were chemical reactions among the kenaf fiber, soy flour, and BASF Acrodur resin. The hot-pressing time had a significant effect on the flexural properties and density of both the kenaf fiber/soy flour composites and kenaf fiber/BASF Acrodur resin composites. However, the effect was opposite for the composites from 10 to 20 min of hot pressing. As the hot-pressing time increased, the flexural properties and density increased for the kenaf fiber/soy flour composites and decreased for the other two composites with BASF Acrodur resin. BASF Acrodur resin reduced the hot-pressing time of the biocomposites. With 28 wt % BASF Acrodur resin (on the basis of 100% solid content) as a binder and with the biocomposites hot-pressed for 10 min, the swelling thickness and water absorption of the composites were reduced by 55 and 64%, and the flexural strength and modulus were improved by 72 and 188%, respectively. More simultaneous failures of the fiber and adhesive were observed at the fracture surface of the kenaf fiber/soy flour/BASF Acrodur resin composite. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 128: 1213-1218, 2013